Reading this book for the first time, I was surprised by the structure of the story. After Robinson is shipwrecked, we learn about his survival methods from his retrospective point-of-view.
Then after Robinson builds a table and begins writing his Journal, Defoe reproduces it within the text and gives the reader another description of the method of Robinson's survival once again, covering scenes that were already explained with lots of detail.
The only difference is that the Journal was written while Robinson was shipwrecked and the book itself is written after he was rescued (within the context of the story).
Why did Defoe think it was a good idea to recap these events?
